1. Field of the Invention
The present invention relates to an apparatus, method, etc. for recording a transmission format signal into a recording medium.
2. Description of Related Art
The MPEG (Moving Picture Experts Group) prescribes a transport stream consisting of compressed audio and video signals. The transport stream is composed of more than one transport packet. There is no data between the transport packets in the transport stream.
The transport packet has at the top thereof a sync_byte of 1 byte to discriminate the transport packet, and has a transport_error_indicator, payload_unit_start_indicator, transport_priority, PID (packet_Identification), transport_scrambling_control, and an adaptation_field_control.
The value of the sync_byte is "01000111 (0.times.47 in hexadecimal notation)". The transport packet has always a length of 188 bytes. A data byte has recorded therein compressed video and audio signals.
A conventional reproducing apparatus capable of reproducing data recorded in such a recording medium will be described with reference to FIG. 1.
In FIG. 1, the reproducing apparatus is generally indicated with a reference 30.
The reproducing apparatus 30 comprises a pickup 31 to read a transport stream recorded in an optical disc 40, an RF amplifier/demodulator circuit 32 to amplify and demodulate the transport stream read out of the optical disc 40, an ECC decoder 33 for error correction, a demultiplexer 34, a video decoder 35 to decode a compressed signal, and an audio decoder 36 to decode a compressed audio signal.
The above-mentioned RF amplifier/demodulator 32 is provided to amplify the received transport stream from the pickup 31, demodulate the amplified signal and supplies the demodulated signal to the ECC decoder 33 in which the received transport stream is subjected to an error correction based on an error correction code. The output of the ECC decoder 33 is supplied to the demultiplexer 34.
The demultiplexer 34 detects a PID of a transport packet supplied from the ECC decoder 33 to judge, according to a preset table, whether the PID is for video or audio. The demultiplexer 34 supplies the video decoder 35 with a data byte part of the transport packet having a video PID while supplying the audio decoder 36 with a data byte part of the transport packet having an audio PID. It should be noted that when the demultiplexer 34 detects a PID not included in the preset table, it will ignore the transport packet having such a PID.
Further the demultiplexer 34 is reset with a signal indicative of the top of a sector generated by the ECC decoder 33, processes 10 transport packets from the sector top, then skips remaining 168 bytes of one sector and repeats the detection of a PID of a transport packet supplied from the ECC decoder 33.
The above-mentioned video decoder 35 decodes a video transport packet supplied from the demultiplexer 34 to provide a video signal. Similarly, the audio decoder 36 decodes an audio transport packet from the demultiplexer 34 to provide an audio signal.
A recording medium such as CD-ROM, magneto-optic disc or the like has recorded therein data in each sector of a power of 2 of bytes such as 2048 bytes or 512 bytes in size suitable for an external recording medium for use with a computer, etc. The 2048 or 512 bytes are suitable for storage of data in such an external storage unit for a computer, etc. When a transport stream is recorded in such a recording medium, the size of transport packet of 188 bytes will be a problem.
For example, it is assumed here that a transport stream is recorded in a CD-ROM having a capacity of 2048 bytes per sector. In this case, since each of transport packets composing the transport stream is of 188 bytes in size, a redundant part takes place in one sector. More particularly, 10 transport packets each of 188 bytes can be recorded in each sector of 2048 bytes, but the sector will have a redundancy of 168 bytes. Namely, since the 188 byte is an aliquant part of the 2048 bytes, the sector will have a redundant part having no data. In the above example, the redundancy is as large as about 8%.
Since such a recording medium has a rather large redundancy of about 8% per sector, a transport stream cannot efficiently be recorded in the recording medium.
Also, even if a transport stream is recorded in the recording medium with no consideration given to the sector and transport packet sizes, the transport stream thus recorded cannot be reproduced for the transport stream is read and reproduced with respect to each sector.